Rotary compressor system



2 SheetsSheet 1 Filed Dec. 2'7, 1957 INVENTOR.

Y VES BREE LLE A lfarneys Jan. 12, 1960 BREELLE ROTARY COMPRESSOR SYSTEM 2 Sheets-Sheet 2 Filed Dec. 2'7, 1957 E U- M m d. m 3 a. m s A m7. w M i United I States Patent ROTARY COMPRESSOR SYSTEM Yves Breelie, Rueil-Malmaison, France, assignor to Institut, Francais du Petr-ole, des Carburants et Lubnfiants,

' Paris, France I Application December 27, 1957,- Serial No. 705,651 Claims priority, application France December 28, 1956 i i 6 Claims. or. 230-139 This invention relates to motor-driven compressor engines, and particularly torotary compressor systems which comprise a compressor or pump unit and, as a driving motor unit, a rotary internal combustion engine.

Rotary internal combustion engines which can be readily applied in the rotary compressor system according to the invention are described, for instance, in, my pending applications Serial. No. 688,908, filed on October 8, 1957,

Serial No. 696,538, 'filcd on November 14, 1957, now.

Patent No. 2,870,752, and Serial No. 698,291, filed on November 22, 1957.

It is an object of my invention to provide an integrated 'motor-compressor system of vastly improved power to from vibrations. I v The known compressor-motor assemblies usually commotorweight ratio, which system is substantially free "prise separately a motor unit and a compressor unit driven by the former via a transmission system. ,So-called free? piston compressors have also been developed by Pesca'r'a 'and others, which assemblies require a separate valve control system and involve the use of a'very heavy mass of the motor-compressor unit, thus leading to an unfavorable ratio of power to weight of the assembly. Furthermore, these systems employ a reciprocating piston movement causing necessarily undesirable vibrations.

tem is characterized ,by the fact that a piston-bearing compressor rotor forms, in combination with at least one gate rotor, the compressor unit ofthe system, and is.

simultaneously the central rotor of a rotary internal combustion engine constituting the driving unit for the compressor unit, thus forming an integral part of the compressor system.

.The rotary compressor system according to my invention thus comprises a piston-bearing central rotor having the'aforesaid double function, at least one gate rotor for cooperating with this central rotor in the compressor unit, and at least two gate rotors for cooperation with the'central rotor in the driving unit, one of the two lastmentioned gate rotors being in each case a combustioncontrolling or a direct combustion rotor, while the other rotor acts as a sealing rotor and is arranged between the intake port for the fluid to be compressed, on the one hand, and the exhaust port on the other hand.

The compressor gate rotor is preferably disposed between the last-mentioned sealing rotor and the intake port for the combustible mixture or the comburant (combustion-sustaining agent).

This invention will be still better understood from the description thereof in connection with the accompanying drawings inwhich:

ice

gine of the carburetor type having a combustion rotor;'

Figure 1A is a fragmentary sectional view of the region of Figure 1 comprising the compressor unit and shows a slightly different arrangement thereof;

Figure 1B is a perspective view of the combustion, rotor shown in Figure 1 and illustrates a slightly different arrangement of the channels leading thereto;

Figure 2 shows a similar view of a rotary compressor system according to the invention comprising a different type of internal combustion rotary engine of the carburetor type; and a Figure 3 shows, again in transverse sectional view, a rotary compressor system according to the invention comprising a rotary internal combustion engine of the fuelj injection type serving as the motor unit of the. system.

Referring to the drawings more in detail, the rotary compressor system illustrated in Figure 1 comprises an engine casing 1 having outer. wall 2 and inner walls '3, and, between these walls 2 and 3, cooling space 4 through which coolant can be caused to flow.

tersect the same so as to freely communicate therewith. The central rotor 5 beers three piston lobes 11, 12 and 13 disposed on the peripheral surface of rotor 5 and distributed, for instance, at equal angles taken at the central axis of rotor 5.

A, compressor gate rotor 14' cooperates with this piston-bearing central rotor 5 inflthe c'ompressorunit of the system according to the invention. This rotor 14 is provided with diametrically opposed wells 15, 16 in the sub-1," stantially cylindrical surface 14a thereof for the passage of the piston lobes 11, 12, 13 therethrough. t

Rotor 14 is mounted on a shaft 17 for rotation therewith in cavity 8, shaft 17 extending parallel to central shaft 6.

The compressor unit further comprises a fluid intake L port 18 for the admission of a gaseous fluid to be'compressed in the portion C of compressor compartmentC of the central bore 7 and an outlet conduit 19 leading from the wall enclosing cavity 8 through the casing 1 to the outside thereof and serving for conducting off the compressed gaseous fluid.

A further conduit 20 is provided in casing 1 for conshall be explained more indetail hereinafter, also serving simultaneously as the power rotor for the internal combustion engine constituting the aforesaid motor unit.

The motor unit of the embodiment of the invention illustrated in Figure 1 further comprises acornbustion rotor 21 mounted on a shaft 22 for rotation thereabout in cavity 9. This rotor 21 is provided with two diametrically opposite wells 23 and 24 in the peripheral surface of the rotor and with two combustion chambers 25, 26 in the interior of the latter, as well as with cooling spaces 27. This motor is constructed as described in detail in my pending patent application Serial No. 688,908 s'upra'.

Apart from the'compression zone C of the compressor unit, the following further zones or compartments can i be distinguished in the .interspace between the portion of I 3 Wall 3 enclosing the central bore 7 and the peripheral surface 5a of central rotor 5. These compartments are the intake compartment I into which intake port 3 opens; the motor compression ZoneII intermediate the leading slope of a piston of rotor and the peripheral wall of rotor 21; a power or expansion compartment III intermediate the peripheral wall 21 and the trailing slope of a piston of rotor 5; and the exhaust zone IV from which exhaust port 31 leads to the outside of the engine.

In order to avoid passage of vast gases from the ct:- haust zone IV to the compression zone C of the cornpressor unit, a sealing rotor 32 having wells 33 and 34 is mounted on a shaft 35 rotatably thereabout in cavity 10, which intersects the central chamber'7 intermediate the aforesaid compartments IV, C.

A conduit 28 from the outside of easing 1 leads to an opening 28a in the portion of wall 3 enclosing cavity 9, while a bypass or transfer channel 29 leads from an opening 29a in cavity 9 to the central bore 7 and opens into the power compartment III in the latter. 7

All rotors of this engine are provided along their peripheral surfaces, and the pistons of central rotor 5 along their ridges 11a, 12a and 13a, with labyrinth-type sealing means constituted by systems of axially extending ribs and grooves. The rotors are disposed so as to leave slight clearances between each other and between the walls of the central chamber and cavities. Sealing is effected exclusively through the turbulence of the gaseous fluid trying to escape through the aforesaid slight V clearance which could be, for instance, about 0.05 millimeter for rotor diameters in the order of -15 centimeters, f-rom zones of higher to those of lower pressure.

This sealing effect in the rotary engines according to the invention is described in detail in my pending patent application Serial No. 688,908 supra.

The rotors are driven synchronizedly by means of a gear train (not shown) provided in an external chamber of the casing 1. Power shaft 6 also bears a starting gear outside thecasing 1, which gear engages the pinion of a starting motor (not shown), for instance a small electric motor.

For the, same reason of synchronized movement of the rotors, in this particular case of Figure 1, the diameters of the rotors 14, 21 and 32 must each be two-thirds that of central rotor 5.

Ignition means such as spark plugs 36 are provided in the end faces of the combustion chambers 25 and 26.

.The location of the spark plugs and fuel ignition means, the nature of the sealing means at the end faces of the rotors, and the cooling system of the rotors and the casing, are described in more detail in my pending application Serial No. 688,908 supra.

In Figure 1A there is shown a somewhat different embodiment of the region of the rotary compressor illustrated in Figure 1, which comprises the compressor gate rotor 14. In this embodiment the intake port 30 and conduit 20 have been combined as a single, intake port 37 close to the cavity 8 housing rotor 14. This embodiment has the advantage of a longer motor compression zone II in the central bore 7. This embodiment of Figure 1A can be adopted when the motor unit consists of a rotary internal combustion engine of the fuel injector type, combustion chambers 25, 26 being provided with a fuel injection nozzle 38 together with or instead of spark plugs 36 of the embodiment shown in Figure 1. The embodiment of Figure 1, on the other hand, is preferable in the case of the motor unit comprising a carburetor-type rotary engine, since a mingling of com pressed gaseous fluid from the well of rotor with the combustion mixture admitted through intake port 30 is effectively prevented.

In the case of air being taken in for compression in the motor unit, when the latter is'of the diesel type, and

when the fluid treated in the compressor unitis also air;

it is not necessary to take the same above-mentioned 4 precautions as in the embodiment of Figure 1, and intake port 37 in Figure lAcombines the functions of both conduit 20 and port 30.

Operation of embodiment shown in Figure I The engine is started, for instance, with the aid of the above-mentioned starting motor acting with its pinion on power shaft 6 and turning the same and rotor 5 together therewith in clockwise direction. Piston lobe 11, having passed intake port 30, will then suction in a fuelair-mixture following its trailing slope. The next following piston 13 compresses this mixture in compartment H of central bore 7, between the leading slope of that piston and the peripheral wall of combustion rotor 21, until well 24, establishes communication between compartment 11 and the combustion chamber 26 of rotor 21, whereupon the mixture is further compressed in that chamber 26 and fully ignited by means of spark plug 36. This ignition takes place at such time that maximum pressure is reached in the combustion chamber approximately at the moment when piston 13 penetrates most completely into well 24, which position would correspond to the upper dead-center in a classical internal combustion engine. The expansion of the inflamed gases then brings motive forces into action on the trailing slope of piston 13, first directly and then byway of the transfer channel 29. At this time piston 11 passes through compartment C and suctions in through intake port 18 and following its trailing slope the fluid to be compressed. Piston 13 meanwhile expels in front of its leading slope the waste gases from the preceding combustion in combustion chamber 25, the gases leaving the engine through exhaust port 31. Piston 13 then passes through well 33, of rotor 32, and, since this piston has passed the intake port 18, it compresses in compartment C between the leading slope of the piston and the peripheral wall of rotor 14, a portion of compressible gaseous fluid, up to the instant when well 15 or 16 of rotor 14 establishes free communication between portion C of compartment C and outlet channel 19 for the compressed fluid. During this phase of the operation, well 23 of rotor 21 establishes free communication between conduit'28 and transfer conduit 29. In order to be able to do so, the distance n--p between openings 28a and 29a of channels 28 and 29, as taken in a projection of that distance on a plane transverse to the rotor axes, must be shorter. than the width c-k, taken in the same plane of each well 23, 24. Furthermore, for instance if scavenging is desired, openings 29a and 28a are at such distance, taken in the same transverse plane, from the line of intersection i between the central bore 7 and cavity 9, that free communication between conduits 28 and 29 is only established by wells 23, 24 after a piston has opened up communication between compartment III and exhaust port 31. As soon as this happens, scavenging gas under pressure from conduit 28 expels the major portion of the waste gases from well 23 or 24 and the combustion chamber through bypass channel 29 and compartment III toward exhaust port 31, until upon further rotation of rotor 21 in clockwise direction, communication between wells 23 or 24 and bypass channel 29 is interrupted.

Since communication between conduit 28 and the well 23m 24 of rotor 21 is still maintained for a certain time,

the respective well is filled with a supercharge of a com- While one of the wells ,23, 24 of rotor 21 thus establishes communication with compartment II, the piston then approximately in the position of piston 13 as illustrated in Figure l enters well 15 or 16 as the case may be of compressor gate rotor 14 and passes through the same. Shortly thereafter, as piston 13 approaches intake port 30 of the motor unit, well 15 or 16 establishes communication with pressure balancing outlet 20, whereby it is avoided that a depression in that well of rotor 14 has a power-consuming effect on the engine as long as there is still communication between that well, for instance 15, of rotor 14 and compartment I.

Figure 2 illustrates an embodiment of the compressor engine according to the invention similar to that shown in Figure 1, but comprises in the motor unit a combustion rotor of the type described in my pending application Serial No. 696,538 supra. This combustion rotor comprises a combustion chamber constituted by wells 23 and 24 in rotor 21 and a diametrically extending connecting passageway or chamber 40, whereby this passageway 40, together with the aforesaid wells 23 and 24, constitutes a single uninterrupted combustion chamber. Furthermore, pressure-equalizing conduit 20 opens into a cavity 8 housing compressor gate rotor 14through opening 20a provided in one of the end walls of the cavity, and similarly, intake port 30 opens at 300: into the central bore 7 of the engine in the region of compartment I in one of the end walls of that compartment, and not in the peripheral wall as in Figure 1. The location of these openings 20a and 30a facilitates the filling of the engines with a fresh explosive mixture and equilibration of pressure in the wells of rotor 14.

In this embodiment, the scavenging conduit 28 is superfluous, the single combustion chamber constituted by spaces 23, 40 and 24 being scavenged directly by the compressed fresh mixture from compartment II.

The sealing eifect of gate rotor 32 can be enhanced by passing a gas under pressure through the interior 32a of the same and into the wells 33 and 34 through openings 41 and 42. In the compressor unit of the engine, fresh fluid to be compressed in portion C of compartment C is admitted through intake port 18a located in one ofthe lateral end faces of bore-7 instead of in the peripheral wall of the latter as shown in Figure 1. r

The operation of the embodiment shown in Figure 2 is substantially identical with that described in connection with Figure 1.

In the rotary compressor engine according to the invention illustrated in Figure 3, the same compressor unit as in Figures 1 and 2 is combined with a motor unit being a rotary internal combustion engine of thefuel injection type as illustrated in my pending patent application Serial No. 698,291 supra.

In this embodiment, the location of the compressor gate rotor 14 in cavity 8 of easing 1 remains substantially the same as in Figures 1 and 2. .The compressor unit further comprises compartment C of the central bore 7, intake port 18 for the admission of a fluid to be compressed, outlet conduit 19 for the compressed fluid, .and a combined intake port and pressure-equalizing conduit 37 as shown in Figure 1A.

Contrary to the previous embodiments, the motor unit of the embodiment illustrated in Figure 3 comprises a central rotor 50 provided with four identical pistons 52,

53, 54 and 55, which are preferably regularly distributed.

about the periphery of the rotor at angles of 360/ 4:90 relative to each other. The motor unit further comprises two gate rotors 56 and 57, which are provided with recesses or wells 58 and 59 and 60 and 61, respectively, adapted for permitting the passage of pistons 52, 53, 54 and 55. Preferred shapes for these recesses are described in particular in my copending patent applications Serial No. 688,908 and Serial No. 696,538 supra.

The diameters of the rotors are such that the latter can rotate without friction against each other. In view of the fact that the central rotor 50 is provided with four pistons, the diameters ofthe gate rotors must each be substantially equal to half the diameter of the central rotor.

A gear train of known construction and described in my patent application Serial No. 688,908 supra, extends the synchronous movement of the rotors via the centrally located shaft 51 of rotor 50.

Since the motor unit shown in Figure 3 is of the fuel injection type, a combustion sustaining agent (oomburant) is introduced through the above-mentioned intake port 37. Casing 1 is further provided with an exhaust port 31 similar to the preceding embodiments. It will be noted that compartments I and II on the one hand and III and IV on .the other hand, extend over a much wider angle, taken at shaft 51, than is the case in the embodiments illustrated in Figures 1 and 2 while maintaining a maximum compression stroke in compartment C. In the inner wall 3 of the casing 1, there is provided a combustion chamber 70 which is located independently of the rotors but adjacent rotor 56, which acts as a combustion gate rotor and steers the functioning of combustion chamber 70.

A fuel injector 71 and an electrical spark plug 72 protrude from the outside of the casing 1 into the combustion chamber 70.

The combustion chamber opens through a wide throat 73 into the compartment III of central bore 7, and at the same time into the peripheral cavity 9 which houses gate .rotor 56. Free communication between the combustion chamber 70 and compartment III is further enlarged by a recess 76in wall 3 enclosing the central bore 7 in the region of that compartment.

Furthermore, the combustion chamber 70 is connected by means of a channel 79 to that well in gate rotor 56 which is on the side of the rotor facing away from the combustion chamber. .Channel 79 opens at 80 into the peripheral cavity 9 in the vicinity of where the latter opens into compartment 11 of. the central bore 7. Channel opening 80 has the cross sectional diameter rs and is located at the distance rt from the central bore 7.

This distance r-t must always be smaller than the circumferential extension ck of the wells 58, 59 in rotor 56 because, otherwise, the introduction of the compressed fluid of compartment II into the combustion chamber 70 would be impossible.

Any insufficiently expanded gases retained in wells 58 or 59 of rotor 56 are provided with an escape through a conduit 81 leading from opening 82 in the wall of cavity 9 to the outside of engine casing 1. Opening 82 has the diameter u-v. A further conduit 83 is provided from the outside of casing 1 toward cavity 9 therein and opens in the latter at 84, which opening has a diameter pq. Opening 84 is located, for instance, intermediate the openings 80 of channel 79,, and 82 of conduit 81, in the wall of cavity 9. Conduit 83 serves for scavenging the burnt residual gases from the wells 58, 59 of rotor 56, as well as from channel 79 and the combustion chamber 70. The shafts of rotors 14, 56 and 57 are, of course, arranged parallel to shaft 51 of central rotor 50.

Operation 0 the embodiment shown in Figure 3 As in the embodiment of Figure 3, the central rotor 50 is assumed to be set in clockwise rotation, for instance by a small starting motor and a gear train described in detail in my copending application Serial No. 688,908 supra. Toward the end of the intake stroke, the comburant, for instance air, is compressed in compartment II between piston 52 and the peripheral wall of rotor 56, and, as soon as well 58 establishes communication with conduit 79, it occupies the latter conduit as well as the combustion chamber 70 and compartment III. After fuel has been injected through injector 71 and the resultant explosive mixture has been ignited, either by self ignition or with the aid of auxiliary spark plug 72, depending on the nature of the'injected fuel and the compression rate, a combustion takes place at constant volume until the instant when communication between compartment II and channel 79 is interrupted due to the rotation of rotor 56. Expansion of the burning gases then leads to the action of motive forces on the trailing slope of piston 53. The provision of recess 76 permits a more complete expansion of the gases, and briefly thereafter, this recess makes it possible to establish, during a short time, a direct free communication between combustion chamber 70 and exhaust conduit 31.

Opening 84 of conduit 83 is located in a different position in the wallet cavity 9 than is the case with the opening 28a of conduit 28 in Figure 1. In a projection on a plane transverse to the axes of the rotors, it is located between opening 80 of channel 79 and opening 82 of conduit 81, so that each well of rotor 56 can establish successively communication, first between conduit 83 and conduit 81 and subsequently between conduit 83 and channel 79, without establishing communication between conduit 81 and channel 79 on the one hand, or between conduit 83 and compartment II on the other hand. This is achieved by maintaining .the distance up and qs, taken in the aforesaid transverse plane shorter, and the distances us and q-t, larger than the width c-k of wells 58 and 59, always taken in the same transverse plane. Conduit 81 may also be omitted, in which case it is suflicient that distance qs in the aforesaid transverse plane be shorter than well width c-k and that the distance qt be-larger than c--k. The arrangement of conduit 81 permits achieving a double scavenging eflect, firstly when the wells of rotor 56 establish communication between conduits 81 and 83, and secondly when these wells establish communication between conduit 83 and channel 79. In the interval between the first and second establishment of communication, the well is filled with gas at the scavenging or supercharge pressure prevailing in condui 83. When, subsequently, the well establishes communication between conduit 83 and channel 79, this gas under scavenging pressure expels the waste gases contained in channel 79, combustion chamber 70, and compartment III toward the exhaust port 31. The position of the pistons of central rotor 50 in compartments III and IV is then such that, due to the recess 76 in the wall of central bore 7, communication between the combustion chamber 70 and the exhaust port 31 remains open for a certain short time. As soon as this communication is interrupted, channel 79, the combustion chamber 70, and compartment III are filled during a short time interval with gas under super-charge pressure introduced from conduit 83, until communication between the latter conduit and channel 79 is interrupted.

Comburant is then normally introduced into these spaces as soon as communication is established between channel 79 and compartment II.

In the compressor unit of the engine illustrated in Figure 3, the fluid to be compressed is introduced via intake port 18, for instance, by being suctioned thereinto following the trailing edge of piston 55 in Figure 3, and as the next following piston 54 emerges from well 60 of rotor 57 and passes intake port 18, it compresses this introduced gaseous fluid between its leading slope and the peripheral wall of rotor 14 until well 16 of rotor 14 establishes communication between compartment C and outlet conduit 19. 7

Although a combined rotary compressor according to the invention has been illustrated by the three foregoing examples in which the compressor unit according to the invention is combined with the above-described three different motor units, this compressor unit can also be combined with all other motor units which comprise a piston-bearing central rotor which is housed in a chamber and adapted for effecting a compression of gaseous fluid in the interspace between the central rotor and the housing therefor, regardless of the. number of pistons borne by the central rotor, the number of peripherally disposed gate rotors, and the number of wells provided for scavenging or supercharging purposes.

in these latter rotors.

Furthermore, independent of the type, of rotary engine used as the motor unit in combination with the abovedescribed compressor unit, the pressure which is to be attained in the latter is determined by the location of rotors 14 and 32 (in Figures 1 and 2), or 14 and 57 (in Figure 3) relative to each other, the axes of these rotors being located in planes passing through the axes of rotor 5, or 50 as the case may be, which planes form an angle a: with each other. The larger the angle 0:, the stronger is the compression rate of the gaseous fluid to be compressed in compartment C of central bore 7.

If the gaseous fluid compressed in this latter compartment is a comburant such as air, a portion thereof leaving outlet conduit 19 may of course be used for introduction into conduit 28 or 83, respectively, and serve Also, a portion of such fluid may be used for cooling the engine and the rotors thereof, as described in my pending application Serial No. 688,908 supra.

Due to the favorable ratio of power to weight of the engine, and the relatively small volume occupied by the same, the compressor systems according to my invention may replace all known compressor motor assemblies and are particularly suitable for use in small watercraft, such as, for instance submarines.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall Within the scope of the appended claims.

What I claim is:

1. A rotary compressor engine comprising, in combination, a casing, a central chamber in said casing at least one compressor unit comprising an intake port for a gaseous fluid to be compressed and an outlet port for the compressed fluid, said intake port opening into said central chamber, a motor unit comprising an intake port for gaseous combustion constituents to be compressed and an outlet port for the combustion products, which latter intake and outlet ports open into said central chamber separately from Said intake and outlet ports of said compressor unit, and each of said inlet ports being free from communication with any of said. outlet ports, and at least one combustion chamber; and, common to both said compressor and said motor unit, a central rotor having a substantially cylindrical rotor body, and at least three rotary pistons protruding from the peripheral surface of said central rotor, said central rotor and said pistons thereon being disposed for rotation in said central chamber; at least three cavities in said casing peripherally intersecting said central chamber, at least three gate rotors each disposed in one of said cavities for rotation therein and engaging said central rotor, thereby subdividing said central chamber into at least three compartments, each of said gate rotors having at least two wells peripherally disposed in the surface of each rotor for the passage of said pistons of said' central rotor therethrough, the axes of said central rotor and said gate rotors being parallel with each other, at least one of said gate rotors being a compression gate rotor controlling the flow of compressed fluid from a predetermined compartment of said central chamber to said outlet for said compressed fluid provided in said casing, which latter outlet port opens into the cavity housing said compression gate rotor, and at least one other of said gate rotors being a rotor controlling by the position of its wells the influx of combustion constituents to and the expansion of gaseous combustion products from said combustion chamber.

2.. A rotary compressor engine as described in claim I, said central chamber and said central rotor disposed in said central chamber defining an annular space having a portion defined by two successive ones of said gate rotors not associated with at least one of said combustion chambers, the compression of gaseous fluid introduced via said intake port being effected in said portion of said annular space.

3. A rotary compressor engine as described in claim 2, an outlet in at least one of said cavities, the gaseous fluid compressed in said portion of said annular space communicating at the end of the compression with one of said outlet ports via one of said wells of that of said gate rotors disposed in that of said cavities having said outlet.

4. In a rotary internal combustion engine having a stator provided with a central bore and at least three cavities peripherally opening into said bore, a central rotor coaxially arranged in said central bore and bearing at least three pistons, and at least three gate rotors, one in each of said cavities and arranged with their central axes parallel with the central axis of said central bore and subdividing the annular space between the body of said central rotor and said central bore into at least three compartments sealed off from one another, each of said gate rotors being provided with wells for the passage of said pistons therethrough, at least one of these gate rotors being continuously associated with at least one combustion chamber, the improvement comprising means for admitting a gaseous fluid to one of said compartments of said annular space being located intermediate two of said gate rotors other than that gate rotor which is continuously associated with said combustion chamber, whereby said gaseous fluid is brought to a determined pressure by the displacement of one of said pistons in the last-mentioned compartment, thus constituting a compression space, whereas the compression of the gaseous combustion constituents takes place in another compartment of said central chamber, and further comprising an outlet conduit for compressed gas provided in said stator, said outlet conduit opening into the cavity housing that one of said gate rotors adjacent to said compression space at which said compressible gaseous fluid attains the required pressure, by way of an outlet port which is so located in said last-mentioned cavity that communication between said outlet port and said compression space is only established at the end of the compression stroke in said compression space and by means of the wells of said last-mentioned gate rotor.

5. The improvement as described in claim 4, wherein the compartment of said annular space in said central bore is located intermediate said gate rotor at which said compressible gaseous fluid attains the required pressure and said rotor associated with said combustion chamber is destined for the intake and compression of the gaseous combustion constituents to be introduced into said combustion space in the normal work-cycle of the engine, and wherein said last-mentioned compartment has an intake port for gaseous combustion constituents, which port is so circumferentially spaced from said gate rotor that each piston of the central rotor moves in the portion of said annular space between said intake port and said gate rotor until communication of the corresponding well of said gate rotor with said last-mentioned compartment is cut off completely, so that said well and said intake port are always sealed against each other, thus preventing penetration of gaseous combustion constituents into said compression space and admixture thereof to the separate gaseous fluid compressed in the latter.

6. The improvement as described in claim 5 further comprising an exhaust channel adjacent said gate rotor which channel connects the wells of the latter rotor with the outside so as to equilibrate the pressure in said wells with that of the outside, said exhaust channel being so positioned that it is always sealed against passage of exhaust gases therefrom toward the outlet conduit for the compressed gaseous fluid by way of a well of said last-mentioned gate rotor.

References Cited in the file of this patent UNITED STATES PATENTS 413,830 Nichols Oct. 29, 1889 619,004 Tygard et al. Feb. 7, 1899 926,641 Cotfey et a1. June 29, 1909 1,093,309 Bouret Apr. 14, 1914 1,238,467 Wherry Aug. 28, 1917 1,286,900 Ashcraft Dec. 10, 1918 1,296,356 Bey Mar. 4, 1919 1,670,229 Balsiger May '15, 1928 2,088,121 Swink July 27, 1937 2,569,640 Mercier et al Oct. 2, 1951 FOREIGN PATENTS 59,058 Austria May 10, 1913 117,195 Sweden Sept. 10, 1946 774,658 Great Britain May 15, 1957 

